Seal insert



FIG. 1 is a plan view of a seal insert showing the new design;

FIG. 2 is a side view thereof, the opposite side being a mirror image;

FIG. 3 is a cross-sectional view along line 3—3 of FIG. 1;

FIG. 4 is a perspective view thereof showing the top and side; and,

FIG. 5 is a perspective view thereof showing the bottom and side.

The ornamental design for a seal insert, as shown and described.